Electrically insulating resin composition and laminate sheet

ABSTRACT

The present invention provides an electrically insulating resin composition including a polysulfone resin including a plurality of sulfonyl groups in the molecule and a polyamide resin, wherein the proportion of the polyamide resin is 1 to 45% by mass. The present invention also provides a laminate sheet obtained by bonding a plurality of sheet materials with a resin composition layer interposed therebetween, wherein the resin composition layer includes a polysulfone resin including a plurality of sulfonyl groups in the molecule and a polyamide resin, and the proportion of the polyamide resin is 1 to 45% by mass.

TECHNICAL FIELD

The present invention relates to an electrically insulating resincomposition. The present invention also relates to a laminate sheetformed of a plurality of sheet materials bonded with a resin compositionlayer obtained by forming the resin composition into a sheet-like shapebeing interposed between the sheet materials.

BACKGROUND ART

Various electrically insulating resin compositions are known in therelated art. For example, an electrically insulating resin compositionused by arranging the composition around a coil wire, which is a heatingbody in a motor, is known.

As such an electrically insulating resin composition, specifically, forexample, an electrically insulating resin composition comprising apolyphenylene sulfide resin having an aromatic hydrocarbon and aplurality of sulfide bonds (—S—) in the molecule and a vinyl copolymer,and formed into a sheet-like shape has been proposed (Patent Document1).

Unfortunately, the electrically insulating resin composition hastracking resistance as electrical insulation properties which isdemanded between one coil wire and another coil wire in the motor, orthe like, while tensile strength or the like may be reduced due to heatgenerated by the coil wire or the like. Thus, heat resistance is notalways sufficient.

Namely, the electrically insulating resin composition is relativelydifficult to have excellent heat resistance and excellent trackingresistance at the same time.

As the conventional laminate sheet, a laminate sheet obtained by bondinga plurality of sheet materials with an electrically insulating resincomposition layer formed in a sheet-like shape being interposedtherebetween is known, for example. Such a laminate sheet can bearranged around the coil wire in the motor as described above, and used.

As such a laminate sheet, specifically, two sheets of a polyamide paperas a sheet material formed of an aromatic polyamide fiber bonded with aresin layer containing a polyphenylene sulfide (PPS) resin beinginterposed therebetween has been proposed, for example (Patent Document2). In such a laminate sheet, peel off of the sheet material from theresin layer is suppressed by adhesiveness between the sheet material andthe resin layer.

Unfortunately, in the laminate sheet, mechanical properties such astensile strength may be reduced by heat generated from the coil wire orthe like in the motor, for example, and heat resistance is not alwayssufficient.

Namely, the laminate sheet is relatively difficult to satisfysuppression in interlayer peel between the sheet material and the resinlayer and to satisfy excellent heat resistance at the same time.

CITATION LIST Patent Document

-   Patent Document 1: Japanese Patent Laid-Open No. 2007-186672-   Patent Document 2: Japanese Patent Laid-Open No. 2010-030222

SUMMARY OF INVENTION Technical Problem

The present invention has been made in consideration of the problems. Anobject of the present invention is to provide an electrically insulatingresin composition having excellent heat resistance and excellentelectrical insulation properties.

Another object of the present invention is to provide a laminate sheethaving excellent heat resistance and satisfying suppression ininterlayer peel.

Solution to Problem

An electrically insulating resin composition according to the presentinvention comprises a polysulfone resin including a plurality ofsulfonyl groups (—SO₂—) in a molecule, and a polyamide resin, wherein aproportion of the polyamide resin is 1 to 45% by mass.

When the electrically insulating resin composition having such aconfiguration contains the polysulfone resin and the polyamide resin ofwhich proportion is 1 to 45% by mass, the electrically insulating resincomposition can have excellent tracking resistance and excellent heatresistance.

Preferably, in the electrically insulating resin composition accordingto the present invention, the polysulfone resin is a polyether sulfoneresin further including a plurality of ether bonds in the molecule, or apolyphenylsulfone resin further including a plurality of aromatichydrocarbons in the molecule.

When the polysulfone resin is the polyether sulfone resin or thepolyphenylsulfone resin, advantageously, the electrically insulatingresin composition has good moldability, and also has excellent trackingresistance and excellent heat resistance.

Preferably, in the electrically insulating resin composition accordingto the present invention, the polyamide resin contains an aromatichydrocarbon. When the polyamide resin contains an aromatic hydrocarbon,advantageously, the electrically insulating resin composition can haveexcellent tracking resistance and more excellent heat resistance.

Preferably, the electrically insulating resin composition according tothe present invention has a CTI value of not less than 130 V in atracking resistance test. Preferably, a tear resistance value is notless than 20 MPa. Preferably, a strength retention of tensile strengthafter 250 hours have passed at 240° C. is not less than 55%.

The electrically insulating resin composition according to the presentinvention is preferably formed into a sheet-like shape. Moreover, theelectrically insulating resin composition according to the presentinvention is preferably used in application of electrical insulation.

A laminate sheet according to the present invention is obtained bybonding a plurality of sheet materials with a resin composition layerinterposed between the sheet materials, wherein the resin compositionlayer comprises a polysulfone resin including a plurality of sulfonylgroups in the molecule and a polyamide resin, and the proportion of thepolyamide resin is 1 to 45% by mass.

The laminate sheet having such a configuration is obtained by bondingthe plurality of sheet materials with the resin composition layerinterposed therebetween, wherein the resin composition layer comprisesthe polysulfone resin and the polyamide resin, and the proportion of thepolyamide resin is 1 to 45% by mass. Thereby, interlayer peel can besuppressed, and excellent heat resistance can be provided.

In the laminate sheet according to the present invention, the sheetmaterials each preferably contain a wholly aromatic polyamide. Thelaminate sheet according to the present invention has an advantage inthat the wholly aromatic polyamide contained in the sheet material canprovide more excellent heat resistance to the laminate sheet.

Preferably, the sheet material is paper produced by a wet papermakingmethod. Preferably, the sheet material is a wholly aromatic polyamidepaper comprising a wholly aromatic polyamide fiber. The laminate sheetaccording to the present invention has an advantage in that moreexcellent heat resistance of the laminate sheet can be provided by thesheet material which is the wholly aromatic polyamide paper comprisingthe wholly aromatic polyamide fiber.

In the laminate sheet according to the present invention, the sheetmaterials each are preferably a non-woven fabric. The laminate sheetaccording to the present invention has an advantage in that thenon-woven fabric as the sheet material can further suppress interlayerpeel between the sheet material and the resin composition layer.

In the laminate sheet according to the present invention, at least asurface of the sheet material on the side of the resin composition layeris preferably subjected to a corona treatment. The laminate sheetaccording to the present invention has an advantage in that theinterlayer peel between the sheet material and the resin compositionlayer can be further suppressed by performing the corona treatment.

In the laminate sheet according to the present invention, thepolysulfone resin is preferably a polyether sulfone resin furtherincluding a plurality of ether bonds in the molecule, or apolyphenylsulfone resin further including a plurality of aromatichydrocarbons in the molecule.

Moreover, in the laminate sheet according to the present invention, thepolyamide resin is preferably a polyamide resin including an aromatichydrocarbon in the molecule. The laminate sheet according to the presentinvention has an advantage in that more excellent heat resistance of thelaminate sheet can be provided by the polyamide resin which is thepolyamide resin including an aromatic hydrocarbon in the molecule.

Preferably, the laminate sheet according to the present inventionfurther comprises a sheet-like pressure-sensitive adhesive layer havingpressure-sensitive adhesiveness, wherein the pressure-sensitive adhesivelayer is disposed on at least one of topmost surfaces of the laminatesheet. Preferably, the pressure-sensitive adhesive layer has flameretardancy that meets the UL94 VTM-0 standard.

The laminate sheet according to the present invention is preferably usedin application of electrical insulation.

Advantageous Effects of Invention

The electrically insulating resin composition according to the presentinvention has effects of providing excellent heat resistance andexcellent electrical insulation properties.

The laminate sheet according to the present invention has effects ofproviding excellent heat resistance and suppressing interlayer peel.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view schematically showing a cross section of alaminate sheet cut in the thickness direction.

FIG. 2 is a sectional view schematically showing a laminate sheetincluding a pressure-sensitive adhesive layer in which the laminatesheet is cut in the thickness direction.

DESCRIPTION OF EMBODIMENTS

Hereinafter, one embodiment of an electrically insulating resincomposition according to the present invention will be described.

The electrically insulating resin composition according to the presentembodiment comprises a polysulfone resin including a plurality ofsulfonyl groups in the molecule and a polyamide resin, wherein theproportion of the polyamide resin is 1 to 45% by mass.

The electrically insulating resin composition may have poor heatresistance when the proportion of the polyamide resin is more than 45%by mass. Moreover, the electrically insulating resin composition mayhave insufficient tracking resistance when the proportion of thepolyamide resin is less than 1% by mass.

In the electrically insulating resin composition, the proportion of thepolyamide resin is preferably not less than 3% by mass, more preferablynot less than 5% by mass, still more preferably not less than 8% bymass, and most preferably not less than 15% by mass. Moreover, theproportion of the polyamide resin is preferably not more than 40% bymass, more preferably not more than 35% by mass, and still morepreferably not more than 32% by mass.

When the proportion of the polyamide resin is not less than 3% by mass,advantageously, the electrically insulating resin composition can obtainmore excellent tracking resistance as electrical insulation properties.When the proportion of the polyamide resin is not more than 40% by mass,advantageously, the electrically insulating resin composition can obtainmore excellent heat resistance.

The polysulfone resin has a molecular structure having a plurality ofsulfonyl groups (—SO₂—).

Examples of the polysulfone resin include polyether sulfone resinsfurther including a plurality of ether bonds (—O—) in the molecule, or apolyphenylsulfone resin further including a plurality of aromatichydrocarbons in the molecule. Further examples of the polysulfone resininclude polyether polyphenylsulfone resins further including a pluralityof ether bonds and a plurality of aromatic hydrocarbons in the molecule.

A preferable polysulfone resin is the polyether polyphenylsulfone resinsbecause the electrically insulating resin composition can have goodmoldability, and can have excellent tracking resistance and excellentheat resistance.

The polyether polyphenylsulfone resin preferably has the molecularstructure represented by the following formula (1):

wherein n is a positive integer indicating a polymerization degree, andusually in the range of 10 to 5000.

As the polyether polyphenylsulfone resin, commercially availableproducts can be used. Examples of those products include “ULTRASON ESeries” made by BASF SE, “Radel A Series” made by Solvay AdvancedPolymers, L.L.C., and “SUMIKAEXCEL Series” made by Sumitomo ChemicalCo., Ltd., and so on.

The polyamide resin is prepared by polymerizing at least a polyaminecompound with a polycarboxylic acid compound by dehydrationcondensation.

Examples of the polyamide resin include polyamide resins having anaromatic hydrocarbon in the molecule, and aliphatic polyamide resinshaving only an aliphatic hydrocarbon as hydrocarbon in the molecule.Among these, polyamide resins having an aromatic hydrocarbon in themolecule are preferable because the electrically insulating resincomposition can have excellent tracking resistance and more excellentheat resistance.

Examples of the polyamide resins having an aromatic hydrocarbon in themolecule include wholly aromatic polyamide resins having only anaromatic hydrocarbon as hydrocarbon in the molecule, and semi-aromaticpolyamide resins having both of an aliphatic hydrocarbon and an aromatichydrocarbon as hydrocarbon in the molecule.

A preferable polyamide resin having an aromatic hydrocarbon in themolecule is the semi-aromatic polyamide resins because trackingresistance and heat resistance are well balanced.

Examples of the polyamine compound used for polymerization of thepolyamide resin specifically include diamine compounds.

Examples of the diamine compound include aliphatic diamines including alinear or branched hydrocarbon group, alicyclic diamines including acyclic saturated hydrocarbon group, and aromatic diamines including anaromatic hydrocarbon group.

Examples of the aliphatic diamines, the alicyclic diamines, or thearomatic diamines include those represented by the following formula(2). In the following formula (2), R₁ represents an aliphatichydrocarbon group having 4 to 12 carbon atoms, an alicyclic hydrocarbongroup including a cyclic saturated hydrocarbon and having 4 to 12 carbonatoms, or a hydrocarbon group having an aromatic ring.

H₂N—R₁—NH₂  (2)

As the aliphatic diamines, nonane diamines in which R₁ in the formula(2) has 9 carbon atoms are preferable, and a mixture of1,9-nonanediamine and 2-methyl-1,8-octanediamine is more preferablebecause the polyamide resin can have more excellent tracking resistance.

Examples of the aromatic diamines include phenylenediamine andxylylenediamine.

Examples of the polycarboxylic acid compound used for polymerization ofthe polyamide resin specifically include dicarboxylic acid compounds.

Examples of the dicarboxylic acid compounds include aliphaticdicarboxylic acids including a linear or branched hydrocarbon group,alicyclic dicarboxylic acids including a cyclic saturated hydrocarbongroup, and aromatic dicarboxylic acids including an aromatic hydrocarbongroup.

Examples of the aliphatic dicarboxylic acids, the alicyclic dicarboxylicacids, or the aromatic dicarboxylic acids include those represented bythe following formula (3). In the following formula (3), R₂ representsan aliphatic hydrocarbon group having 4 to 25 carbon atoms, an alicyclichydrocarbon group including a cyclic saturated hydrocarbon and having 4to 12 carbon atoms, or a hydrocarbon group having an aromatic ring.

HOOC—R₂—COOH  (3)

Examples of the aliphatic dicarboxylic acids include adipic acid andsebacic acid.

Examples of the aromatic dicarboxylic acids include terephthalic acid,methylterephthalic acid, and naphthalenedicarboxylic acid. A preferablearomatic dicarboxylic acid is terephthalic acid because the polyamideresin can have more excellent heat resistance.

The polyamide resin may be prepared by polymerizing one of the diaminecompounds with one of the dicarboxylic acid compounds, or may beprepared by polymerizing the diamine compounds in combination with thedicarboxylic acid compounds. When necessary, the polyamide resin may beprepared by polymerizing the diamine compound and the dicarboxylic acidcompound with other compound.

As described above, as the polyamide resin, the semi-aromatic polyamideresins are preferable. As the semi-aromatic polyamide resins, thoseprepared by polymerizing the aliphatic diamine as the diamine compoundwith the aromatic dicarboxylic acid as the dicarboxylic acid compoundare more preferable, and those prepared by polymerizing nonanediamine asthe aliphatic diamine with terephthalic acid as the aromaticdicarboxylic acid (PA9T) are particularly preferable.

In the electrically insulating resin composition, a variety of additivesmay be blended.

Examples of the additives include: pressure-sensitive adhesives such asalkylphenol resins, alkylphenol-acetylene resins, xylene resins,coumarone-indene resins, terpene resins, and rosin; bromine flameretardants such as polybromodiphenyl oxide and tetrabromobisphenol A;chlorine flame retardants such as chlorinated paraffin andperchlorocyclodecane; phosphorus flame retardants such as phosphoricacid ester and halogen-containing phosphoric acid ester; boron flameretardants; oxide flame retardants such as antimony trioxide; metalhydrate compounds such as aluminum hydroxide and magnesium hydroxide;antioxidants such as phenol antioxidants, phosphorus antioxidants, andsulfur antioxidants; inorganic fillers such as silica, clay, calciumcarbonate, barium carbonate, strontium carbonate, aluminum oxide,magnesium oxide, boron nitride, silicon nitride, and aluminum nitride;and ordinary blending components for plastics such as a heat stabilizer,a light stabilizer, an ultraviolet absorbing agent, a lubricant, apigment, a crosslinking agent, a crosslinking aid, a silane couplingagent, and a titanate coupling agent. Examples of the additives includearomatic polyamide fibers, and montmorillonite having a particle size ofseveral to several hundreds nanometers. These additives can be used in aproportion of 0.1 to 5 parts by weight based on 100 parts by weight ofthe electrically insulating resin composition, for example.

The electrically insulating resin composition preferably has a CTI valueof not less than 130 V in the tracking resistance test, which ismeasured by the method described in Examples, because more excellenttracking resistance as the electrical insulation properties can beobtained.

The electrically insulating resin composition preferably has a strengthretention of tensile strength of not less than 55% after 250 hours havepassed at 240° C., which is measured by the method described inExamples, because more excellent heat resistance can be obtained.

The electrically insulating resin composition preferably has a tearresistance value of not less than 20 MPa, which is measured by themethod described in Examples, because more excellent tear resistance canbe obtained.

The electrically insulating resin composition can be produced by mixingat least the polysulfone resin and the polyamide resin using an ordinarymixing and stirring apparatus such as a kneader, a pressure kneader, akneading roll, a Banbury mixer, and a twin screw extruder.Alternatively, the electrically insulating resin composition can beproduced by using a dry blend, for example, and mixing and stirring thedry blend in a cylinder or the like of an extruder.

The electrically insulating resin composition can be molded into asheet-like shape using an extruder including a T die, an injectionmolding machine, or the like. A laminate sheet can be produced bybonding a sheet material such as paper formed of an aromatic amide resinfiber to both surfaces of the electrically insulating resin compositionmolded into a sheet-like shape, for example.

The produced laminate sheet can be suitably used in application thatneeds electrical insulation properties and heat resistance.Specifically, for example, the laminate sheet can be used inapplications of a sheet material for electrical insulation used byarranging the sheet around a coil wire, which is a heating body in amotor, a sheet material for electrical insulation used in transformers,bus bars, capacitors, cables, and the like, and insulating films forelectric circuit boards.

Next, a laminate sheet according to one embodiment of the presentinvention will be described with reference to the drawings. FIG. 1 andFIG. 2 each are a sectional view schematically showing a cross sectionof the laminate sheet according to the present embodiment cut in thethickness direction.

As shown in FIG. 1, a laminate sheet 1 according to the presentembodiment is obtained by bonding a plurality of sheet materials 3 witha sheet-like resin composition layer 2 interposed therebetween, whereinthe resin composition layer 2 comprises the polysulfone resin includinga plurality of sulfonyl groups in the molecule and the polyamide resin,and the proportion of the polyamide resin is 1 to 45% by mass.

The resin composition layer 2 is obtained by forming the resincomposition comprising the polysulfone resin and the polyamide resininto a sheet-like shape such that the proportion of the above polyamideresin is 1 to 45% by mass. Namely, the resin composition layer 2 isobtained by forming the above electrically insulating resin compositioninto a sheet-like shape.

The resin composition layer 2 may have inferior heat resistance when theproportion of the polyamide resin is more than 45% by mass. When theproportion of the polyamide resin is less than 1% by mass, interlayerpeel between the resin composition layer 2 and the sheet material 3 maybe likely to occur.

In the resin composition layer 2, the proportion of the polyamide resinis preferably not less than 3% by mass, more preferably not less than 5%by mass, still more preferably not less than 8% by mass, and mostpreferably not less than 15% by mass. The proportion of the polyamideresin is preferably not more than 40% by mass, more preferably not morethan 35% by mass, and still more preferably not more than 32% by mass.

When the proportion of the polyamide resin is not less than 3% by mass,advantageously, interlayer peel between the resin composition layer 2and the sheet material 3 can be difficult to occur. When the proportionof the polyamide resin is not more than 40% by mass, advantageously, theresin composition layer 2 can have more excellent heat resistance andmore excellent flame retardancy.

The thickness of the resin composition layer 2 is not particularlylimited, and usually is 1 μm to 500 μm.

Examples of the polysulfone resin and the polyamide resin include thesame ones as those described above.

The polyamide resins having an aromatic hydrocarbon in the molecule arepreferable as the polyamide resins because the resin composition layer 2can have more excellent heat resistance. The semi-aromatic polyamideresins are preferable as the polyamide resins because more excellentheat resistance can be obtained and interlayer peel between the sheetmaterial 3 and the resin composition layer 2 can be further suppressed.

Nonane diamines in which R₁ in the formula (2) has 9 carbon atoms arepreferable, and a mixture of 1,9-nonanediamine and2-methyl-1,8-octanediamine is more preferable as the aliphatic diamineused for polymerization of the polyamide resin because interlayer peelbetween the sheet material and the resin composition layer can befurther suppressed.

Terephthalic acid is preferable as the aromatic dicarboxylic acid usedfor polymerization of the polyamide resin because the polyamide resincan have more excellent heat resistance.

As described above, as the polyamide resin, the semi-aromatic polyamideresins are preferable. As the semi-aromatic polyamide resin, thoseprepared by polymerizing the aliphatic diamine as the diamine compoundwith the aromatic dicarboxylic acid as the dicarboxylic acid compoundare more preferable, and those prepared by polymerizing nonanediamine asthe aliphatic diamine with terephthalic acid as the aromaticdicarboxylic acid (PA9T) are particularly preferable.

As described above, a variety of additives may be blended with the resincomposition layer 2.

The sheet material 3 may be any sheet material having a sheet-likeshape, and is not particularly limited. The thickness is notparticularly limited, and usually is 10 to 100 μm. As shown in FIG. 1,usually, two sheet materials 3 are included in the laminate sheet.

Examples of the sheet material 3 include paper, non-woven fabrics, andfilms. As the sheet material 3, paper or non-woven fabrics arepreferable because interlayer peel between the sheet material and theresin composition layer can be further suppressed.

Examples of the sheet material 3 include those produced by a wetpapermaking method, those produced in the air by a dry method, and soon.

As the sheet material 3, the paper produced by the wet papermakingmethod is preferable because interlayer peel between the sheet materialand the resin composition layer can be further suppressed.

Examples of a material for the sheet material 3 include syntheticpolymer compounds such as polyamides and polyesters, and natural polymercompounds such as cellulose. Polyamides are preferable becauseinterlayer peel between the sheet material and the resin compositionlayer can be further suppressed.

Examples of the polyamide include wholly aromatic polyamides in whichall of the constituent monomers have an aromatic hydrocarbon, aliphaticpolyamides in which all of the constituent monomers have only analiphatic hydrocarbon as hydrocarbon, and semi-aromatic polyamides inwhich part of the constituent monomers has an aromatic hydrocarbon. Thewholly aromatic polyamides are preferable because interlayer peelbetween the sheet material and the resin composition layer can befurther suppressed. Namely, the sheet material 3 preferably contains thewholly aromatic polyamide.

As the sheet material 3, a wholly aromatic polyamide paper comprising awholly aromatic polyamide fiber is more preferable, a wholly aromaticpolyamide paper produced using a wholly aromatic polyamide fiber by thewet papermaking method is still more preferable because interlayer peelbetween the sheet material and the resin composition layer can befurther more suppressed and excellent flame retardancy is obtained.

Examples of the wholly aromatic polyamide paper include those formed ofmainly a wholly aromatic polyamide fiber obtained by forming acondensation polymerization product of phenylenediamine and phthalicacid (wholly aromatic polyamide) into fibers, in which a portion exceptan amide group in the condensation polymerization product is composed ofa benzene ring.

The wholly aromatic polyamide paper preferably has a weight of not lessthan 5 g/m² because the mechanical properties are excellent, andhandling is easy in the step of producing the laminate sheet. At aweight of not less than 5 g/m², advantageously, insufficient mechanicalstrength is avoided, and thus the laminate sheet is difficult to breakduring production.

Other component may be blended with the wholly aromatic polyamide paper.Examples of the other component include organic fibers such aspolyphenylene sulfide fibers, polyether ether ketone fibers, polyesterfibers, arylate fibers, liquid crystal polyester fibers, andpolyethylene naphthalate fiber; or inorganic fibers such as glassfibers, rock wool, asbestos, boron fibers, and alumina fibers.

As the wholly aromatic polyamide paper, commercially available productssuch as a trade name “NOMEX” made by E. I. du Pont de Nemours andCompany can be used.

Preferably, the surface of the sheet material 3 on the side of the resincomposition layer 2 is subjected to a corona treatment. By performingthe corona treatment, advantageously, interlayer peel between the sheetmaterial and the resin composition layer can be further suppressed.

The corona treatment is a surface roughening treatment by performing adischarging treatment on one of the surfaces of the sheet material 3contacting the resin composition layer 2 to generate a polar carboxylgroup or a hydroxyl group. As the corona treatment, known ordinarymethods can be used.

The laminate sheet 1 further includes a sheet-like pressure-sensitiveadhesive layer 4 having pressure-sensitive adhesiveness. Thepressure-sensitive adhesive layer 4 may be disposed on at least one ofthe topmost surfaces of the laminate sheet. The pressure-sensitiveadhesive layer 4 may be disposed only on one of the surfaces of thelaminate sheet 1, or may be disposed on both of the surfaces of thelaminate sheet 1 as shown in FIG. 2.

When the laminate sheet 1 includes the pressure-sensitive adhesive layer4 on the topmost surface(s), the laminate sheet 1 can be used by bondingthe pressure-sensitive adhesive layer 4 to an adherent. Specifically,the laminate sheet 1 can be used in applications that need heatresistance and electrical insulation properties; for example, thelaminate sheet 1 can be used as a sheet-like electrically insulatingmaterial in the state where the pressure-sensitive adhesive layer 4 isbonded to a plate-like conductor made of a metal.

The pressure-sensitive adhesive layer 4 that can be included in thelaminate sheet 1 contains at least a pressure-sensitive adhesivecontaining a known ordinary polymer.

Examples of the pressure-sensitive adhesive include acrylicpressure-sensitive adhesives containing an acrylic polymer having(meth)acrylate ester as a basic structural unit, rubberpressure-sensitive adhesives containing an elastomeric polymer such assynthetic rubbers and natural rubbers, silicone pressure-sensitiveadhesives containing silicone polymer, polyester pressure-sensitiveadhesives containing a polyester polymer, and polyurethanepressure-sensitive adhesives containing a polyurethane polymer. Amongthese, the acrylic pressure-sensitive adhesives are preferable becauseof their excellent pressure-sensitive adhesive properties andweatherability.

Preferably, the pressure-sensitive adhesive layer 4 contains acrosslinking agent that can crosslink the polymer in thepressure-sensitive adhesive, because more excellent pressure-sensitiveadhesive force and durability are obtained. Examples of the crosslinkingagent include isocyanate crosslinking agents, epoxy crosslinking agents,melamine crosslinking agents, oxazoline crosslinking agents,carbodiimide crosslinking agents, aziridine crosslinking agents, andmetalchelate crosslinking agents. More preferably, thepressure-sensitive adhesive layer 4 further contains a tackifying resinsuch as rosin resins, terpene resins, aliphatic petroleum resins,aromatic petroleum resins, copolymerized petroleum resins, alicyclicpetroleum resins, xylene resins, or elastomer resins because moreexcellent pressure-sensitive adhesive force and durability are obtained.

Other than the pressure-sensitive adhesives, crosslinking agents, andtackifying resins described above, the pressure-sensitive adhesive layer4 can contain an additive usually added to rubber and plastics such as adispersant, an age resistor, an antioxidant, a processing aid, astabilizer, an antifoaming agent, a thickener, and a pigment.

The pressure-sensitive adhesive layer 4 may have a configurationobtained by mixing a flame retardant described later and thepressure-sensitive adhesive to produce a mixture and forming the mixtureinto a sheet-like shape, for example.

Alternatively, the pressure-sensitive adhesive layer 4 may be configuredto have a sheet-like base material for enhancing shape retention of thepressure-sensitive adhesive layer, and have a layer-like body containingat least the pressure-sensitive adhesive and disposed on both surfacesof the base material, for example.

Examples of the base material that the pressure-sensitive adhesive layer4 can have include paper base materials such as paper; fiber basematerials such as fabrics, non-woven fabrics, and nets; metallic basematerials such as metallic foils and metal plates; plastic basematerials such as plastic films; rubber base materials such as rubbersheets; and foaming base materials such as foaming sheets. Examples ofthe base material also include laminate base materials obtained bylaminating these base materials. As the laminate base material, thoseobtained by laminating a plurality of the plastic base materials, thosecontaining at least the plastic base material, and so on are preferable.

Examples of a material for the plastic base material include olefinresins containing α-olefin such as polyethylene (PE), polypropylene(PP), ethylene-propylene copolymers, and ethylene-vinyl acetatecopolymers (EVA) as a monomer component; polyester resins such aspolyethylene terephthalate (PET), polyethylene naphthalate (PEN),polybutylene terephthalate (PBT); polyvinyl chloride (PVC) resins; vinylacetate resins; polyphenylene sulfide (PPS) resins; polyamide resinssuch as aliphatic polyamides and wholly aromatic polyamides; polyimideresins; and polyether ether ketone (PEEK) resins. These materials forthe plastic base material can be used alone or in combination of two ormore.

Preferably, the laminate sheet 1 has a flame retardancy that meets theUL94 VTM-0 standard because the laminate sheet 1 can be used inapplications of insulating materials for terminals that need relativelyhigh flame retardancy. The laminate sheet 1 has such flame retardancy,and therefore can be used in applications of an insulating material forterminals in power modules such as Insulated Gate Bipolar Transistor(IGBT) modules.

The UL94 standard is a standard for a burning test established byUnderwriters Laboratories Inc., the U.S., and usually known.Specifically, the flame retardancy that meets the UL94 VTM-0 standard isconsidered accepted according to the method described in Examples.

For the laminate sheet 1 to have the flame retardancy that meets theUL94 VTM-0 standard, the pressure-sensitive adhesive layer 4 preferablyhas the flame retardancy that meets the standard. When thepressure-sensitive adhesive layer 4 properly contains a proper amount ofa known ordinary flame retardant, for example, the pressure-sensitiveadhesive layer 4 can have the flame retardancy that meets the UL94 VTM-0standard.

The flame retardant is not particularly limited. Examples thereofinclude: chlorine compounds such as chlorinated paraffin, chlorinateddiphenyl, chlorinated ethane, chlorinated polyethylene, chlorinatedpolyphenyl, chlorinated diphenyl, perchlorocyclopentadecanone, andtetrachlorobisphenol A; bromine compounds such as brominated paraffin,brominated polyphenyl, tetrabromoethane, tetrabromobenzene,decabromodiphenyl oxide, octabromodiphenyl oxide,hexabromocyclododecane, bis(tribromophenoxy)ethane,bigtribromophenoxy)ethane, ethylenebistetrabromophthalimide,hexabromobenzene, polydibromophenylene oxide, tetrabromobisphenol A,tris(2,3-dibromopropyl-1)isocyanurate, tribromophenol allyl ether,brominated polystyrene, tribromoneopentyl alcohol,dibromodichloropropane, and dibromotetrafluoroethane; phosphoric acidesters such as triphenyl phosphate (TPP), tricresyl phosphate (TCP),trixylenyl phosphate (TXP), cresyldiphenyl phosphate (CDP),xylenyldiphenyl phosphate (XDP), resorcinol-bis-(diphenylphosphate),2-ethylhexyldiphenyl phosphate, dimethyl methyl phosphate,triallylphosphate (Reofos), and alkyl phosphate; halogen-containingphosphoric acid esters such as trischloroethyl phosphate,trisdichloropropyl phosphate, tris-β-chloropropyl phosphate,tris(tribromophenyl)phosphate, tris(tribromophenyl)phosphate,tris(tribromoneopentyl)phosphate, anddiethyl-N,N-bis(2-hydroxyethyl)aminomethyl phosphonate; condensedphosphoric acid esters such as aromatic condensed phosphoric acid estersand halogen-containing condensed phosphoric acid esters; polyphosphoricacid salt compounds such as ammonium polyphosphate andpolychlorophosphite; inorganic oxides such as antimony trioxide,antimony pentoxide, zirconium oxide, aluminum hydroxide, ferrichydroxide, and zinc borate; metal carbonates such as basic magnesiumcarbonate, magnesium carbonate-calcium, calcium carbonate, bariumcarbonate, and dolomite; and metal hydrates such as hydrotalcite andborax (hydrates of metal compounds).

The amount of the flame retardant contained in the pressure-sensitiveadhesive layer 4 is not particularly limited. From the viewpoint ofproviding the flame retardancy and pressure-sensitive adhesiveproperties of the pressure-sensitive adhesive layer at the same time,the amount is preferably not more than 250 parts by weight, morepreferably not less than 1 part by weight and not more than 250 parts byweight, and still more preferably not less than 5 parts by weight andnot more than 200 parts by weight based on 100 parts by weight of thepressure-sensitive adhesive. When not more than 250 parts by weight ofthe flame retardant is contained based on 100 parts by weight of thepressure-sensitive adhesive, advantageously, reduction inpressure-sensitive adhesiveness by bleeding out the flame retardant canbe suppressed.

Preferably, the laminate sheet 1 has a strength retention of tensilestrength of not less than 50% after 250 hours have passed at 240° C.,which is measured by the method described in Examples.

Preferably, the laminate sheet 1 is configured such that the sheetmaterial 3 is disposed contacting each of the surfaces of the resincomposition layer 2, and the interlayer adhesive force between the resincomposition layer 2 and the sheet material 3 is larger than the cohesivefailure force of the resin composition layer 2 and that of the sheetmaterial 3. According to such a configuration, interlayer peel betweenthe resin composition layer 2 and the sheet material 3 can besuppressed.

Subsequently, a method for producing the laminate sheet 1 will bedescribed.

For example, the laminate sheet 1 can be produced by sandwiching theresin composition layer 2 with two sheet materials 3, and pressing thesheet materials 3 toward each other.

The resin composition layer 2 can be produced by mixing the polysulfoneresin and the polyamide resin using an ordinary mixing device such as akneader, a pressure kneader, a kneading roll, a Banbury mixer, and atwin screw extruder to prepare the resin composition, and extruding theresin composition into a sheet-like shape using an extruder to which aT-die is attached.

The laminate sheet 1 including the pressure-sensitive adhesive layer 4can be produced by sandwiching the resin composition layer 2 with twosheet materials 3 and pressing the sheet materials 3 as described above,and bonding the pressure-sensitive adhesive layer of a commerciallyavailable pressure-sensitive adhesive tape to at least one surface ofthe pressed sheet, for example.

Utilizing the electrical insulation properties that the laminate sheet 1has, the laminate sheet 1 can be used as sheets for electricalinsulation used in motors of automobiles and the like, sheets forelectrical insulation used in transformers, and sheets for electricalinsulation used for bus bars, for example.

The electrically insulating resin composition and laminate sheetaccording to the present embodiment are as described above, but thepresent invention will not be limited to the laminate sheet exemplifiedabove.

Moreover, the present invention can use various embodiments used inordinary electrically insulating resin compositions and laminate sheets.

EXAMPLES

Next, the present invention will be described more in detail usingExamples, but the present invention will not be limited to these.

Example 1

As the polysulfone resin, a polyether polyphenylsulfone resin (PES)resin (made by Solvay Advanced Polymers, L. L. C., trade name “RadelA-300A”) including a plurality of sulfonyl groups, a plurality of etherbonds, and a plurality of aromatic hydrocarbons was used.

Meanwhile, as the polyamide resin, a polyamide (PA) resin comprising aterephthalic acid unit and a nonanediamine unit (PAST made by KurarayCo., Ltd., trade name “Genestar N1000A”) was used.

The PES resin was mixed with the PA resin at a mass ratio of PES/PA=95/5using a twin screw kneader (made by TECHNOVEL CORPORATION) at 310° C. toproduce an electrically insulating resin composition.

Example 2

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that the mass ratio of the PES resin tothe PA resin was PES/PA=90/10.

Example 3

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that the mass ratio of the PES resin tothe PA resin was PES/PA=80/20.

Example 4

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that the mass ratio of the PES resin tothe PA resin was PES/PA=70/30.

Example 5

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that the mass ratio of the PES resin tothe PA resin was PES/PA=60/40.

Comparative Example 1

Instead of the electrically insulating resin composition, only the PESresin was used.

Comparative Example 2

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that the mass ratio of the PES resin tothe PA resin was PES/PA=50/50.

Comparative Example 3

An electrically insulating resin composition was produced in the samemanner as in Example 1 except that mass ratio of the PES resin to the PAresin was PES/PA=30/70.

Comparative Example 4

Instead of the electrically insulating resin composition, a polyethylenenaphthalate (PEN) film (made by Teijin DuPont Films Japan Limited, tradename “Teonex 100 μm”) was prepared.

Comparative Example 5

Instead of the electrically insulating resin composition, polyphenylenesulfide (PPS) film (made by Toray Industries, Inc., trade name “TORELINA100 μm”) was prepared.

<Evaluation of Long-Term Heat Resistance>

Each of the produced electrically insulating resin compositions or theresin was molded into a sheet-like shape having a thickness of 100 μm byextrusion molding at 310° C. to produce a sheet body.

Next, the sheet body was cut along the flow direction during the moldingat a width of 15 mm to produce a test sample. The produced test samplewas left for 250 hours in a thermostat heated to 240° C. Before andafter the test sample was left in the thermostat, a tensile test wasperformed on the test sample on the test condition of 200 mm/min and agauge length of 100 mm, and the tensile strength was measured. Then, thestrength retention was calculated by the following expression:

strength retention(%)={(tensile strength after the test sample isleft)/(tensile strength before the test sample is left)}×100

The films in Comparative Examples 4 and 5 were evaluated in the samemanner as above.

<Evaluation of Tracking Resistance (Tracking Resistance Test)>

According to JIS C2134, the CTI (Comparative Tracking Index) value inthe sheet body or the film was measured.

<Evaluation of Tear Resistance>

According to JIS C2111, the tear resistance value was measured in themachine direction (MD) of the sheet body or film and in the transversedirection (TD) of the sheet body or film.

The results of evaluation of the long-term heat resistance (strengthretention), tracking resistance (CTI value), and tear resistance (tearresistance value) in the sheet bodies using the electrically insulatingresin composition or resin or the film in Examples and ComparativeExamples are shown in Table 1 and Table 2.

TABLE 1 Example Example Example Example Example 1 2 3 4 5 Blended resinsPES/PA PES/PA 95/5 90/10 80/20 70/30 60/40 Strength 84 70 67 63 60retention (%) CTI value (V) 150 150 175 175 200 Tear resistance 105 115108 101 38 MD tear resistance (MPa) Tear resistance 109 106 159 125 110TD tear resistance (MPa)

TABLE 2 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 Blended resins PESPES/PA PEN PPS PES/PA — 50/50 30/70 — — Strength retention 84 24 13 3951 (%) CTI value (V) 125 250 600 175 175 Tear resistance 85 4 39 300 270MD tear resistance (MPa) Tear resistance 104 141 94 393 220 TD tearresistance (MPa)

Further, a laminate sheet was produced, and the performance of thelaminate sheet was evaluated.

Example 6

Two wholly aromatic polyamide paper (made by E. I. du Pont de Nemoursand Company, trade name “NOMEX T410,” thickness of 50 μm) were used asthe sheet material.

Meanwhile, as the polysulfone resin, a polyether polyphenylsulfone (PES)resin containing a plurality of sulfonyl groups, a plurality of etherbonds, and a plurality of aromatic hydrocarbons (made by Solvay AdvancedPolymers, L.L.C., trade name “Radel A-300A”) was used.

As the polyamide resin, a polyamide (PA) resin comprising a terephthalicacid unit and a nonanediamine unit (PA9T made by Kuraray Co., Ltd.,trade name “Genestar N1000A”) was used.

Next, the PES resin was mixed with the PA resin at a mass ratio ofPES/PA=95/5 using a twin screw kneader (made by TECHNOVEL CORPORATION)at 310° C. to prepare a resin composition.

Subsequently, the resin composition was molded into a sheet-like shapehaving a thickness of 100 μm by extrusion molding at 310° C. to form aresin composition layer. A wholly aromatic polyamide paper was disposedon both surfaces of the resin composition layer. Then, the resincomposition layer with the wholly aromatic polyamide paper wassandwiched by two metal plates, and pressed at a pressure of 200 N/cm²for 60 seconds using a heat press heated to 350° C. Thus, a laminatesheet (thickness of approximately 200 μm) was produced.

Example 7

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=90/10 in the resin compositionlayer, and the sheet material was subjected to a corona treatment andthe surface subjected to the corona treatment was disposed contactingthe resin composition layer.

The corona treatment was performed using a “500 Series” made by PILLARTECHNOLOGIES, Inc. as an apparatus under an atmospheric pressure on thecondition of an output of 500 W, a treatment rate of 4 m/min, and asample width of 0.4 m.

Example 8

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=90/10 in the resin compositionlayer.

Example 9

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=80/20 in the resin compositionlayer.

Example 10

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=80/20 in the resin compositionlayer, and the sheet material subjected to the same corona treatment asthat in Example 7 was used.

Example 11

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=70/30 in the resin compositionlayer.

Example 12

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=60/40 in the resin compositionlayer.

Example 13

A pressure-sensitive adhesive layer A below was bonded to one surface ofthe laminate sheet produced in Example 10 to produce a laminate sheetincluding a pressure-sensitive adhesive layer.

pressure-sensitive adhesive layer A:obtained by removing a releasing material from a flame retardant acrylicpressure-sensitive adhesive double-sided tape (made by NITTO DENKOCORPORATION, trade name “No. 5011N”)(thickness of 150 μm)(in which a pressure-sensitive adhesive layer including an acrylicpressure-sensitive adhesive was laminated on both surfaces of anon-woven fabric) (the UL94 VTM-0 standard was met)

Example 14

A pressure-sensitive adhesive layer B below was bonded to one surface ofthe laminate sheet produced in Example 10 to produce a laminate sheetincluding a pressure-sensitive adhesive layer.

pressure-sensitive adhesive layer B:obtained by removing a releasing material from an acrylicpressure-sensitive adhesive double-sided tape (made by NITTO DENKOCORPORATION, trade name “No. 500”)(thickness of 170 μm)(in which a pressure-sensitive adhesive layer including an acrylicpressure-sensitive adhesive was laminated on both surfaces of anon-woven fabric) (the UL94 VTM-0 standard was not met)

Comparative Example 6

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed using only the PES resin.

Comparative Example 7

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed using only the PES resin,and the sheet material subjected to the same corona treatment as that inExample 7 was used.

Comparative Example 8

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=50/50 in the resin compositionlayer.

Comparative Example 9

A laminate sheet was produced in the same manner as in Example 6 exceptthat the resin composition layer was formed such that the mass ratio ofthe PES resin to the PA resin was PES/PA=30/70 in the resin compositionlayer.

Comparative Example 10

A laminate sheet was produced in the same manner as in Example 6 exceptthat a polyethylene naphthalate (PEN) film (made by Teijin DuPont FilmsJapan Limited, trade name “Teonex 100 μm”) was used instead of the resincomposition layer, and the sheet material subjected to the same coronatreatment as that in Example 7 was used.

Comparative Example 11

A laminate sheet was produced in the same manner as in Example 6 exceptthat a polyphenylene sulfide (PPS) film (made by Toray Industries, Inc.,trade name “TORELINA 100 μm”) was used instead of the resin compositionlayer, and the sheet material subjected to the same corona treatment asthat in Example 7 was used.

Comparative Example 12

The pressure-sensitive adhesive layer A was bonded to one surface of thelaminate sheet produced in Comparative Example 10 to produce a laminatesheet including a pressure-sensitive adhesive layer.

<Evaluation of Long-Term Heat Resistance>

The produced laminate sheet was cut in the flow direction of the resincomposition layer at a width of 15 mm to produce a test sample. Theproduced test sample was left for 250 hours in a thermostat heated to240° C. Before and after the test sample was left in the thermostat, atensile test was performed on the test sample on the test condition of200 mm/min and a gauge length of 100 mm, and the tensile strength wasmeasured. Then, the strength retention was calculated by the followingexpression:

strength retention(%)={(tensile strength after the test sample isleft)/(tensile strength before the test sample is left)}×100

<Evaluation of Releasing Properties>

The produced laminate sheet was cut in the flow direction of the resincomposition layer during the molding at a width of 10 mm to prepare atest sample. The produced laminate sheet was immersed in pure water at23° C. for 24 hours, and cut at a width of 10 mm in the same manner toprepare a test sample.

In these test samples, the sheet material (wholly aromatic polyamidepaper) was pulled at 90° to the resin composition layer and the rate of200 mm/min, and peeled at 25° C. The state in peeling was observed.Then, the result was evaluated according to the three grades below:

∘: peeled by breakage of the sheet material

Δ: peeled by partial breakage of the sheet material

x: peeled by interlayer peel between the sheet material and the resincomposition layer

<Evaluation of Flame Retardancy>

A burning test was performed according to the UL94 standard, and theflame retardancy was evaluated.

Specifically, first, each of the laminate sheets produced in Examplesand Comparative Examples was cut into a size of 50 mm×200 mm. Thereby,five test pieces were obtained from each of the laminate sheets.

The test piece was rolled into a cylindrical shape, and disposed toextend in the vertical direction. The upper end of the test piece wasfixed to hang the test piece. A gauge length was marked at a position125 mm from the lower end of the test piece. Cotton was placedimmediately under the test piece, and a flame was applied to the lowerend of the test piece for 3 seconds to perform ignition operation. Theignition operation was performed twice in total.

Then, it was considered passed (∘) when the test piece met all the itemsbelow. Namely, it was considered passed when the test piece met theVTM-0 standard. Meanwhile, it was considered failed (x) when the testpiece did not meet one of the items below.

1. The total flaming combustion time of each of the test pieces (thetotal of the burning time after application of a first flame and theburning time after application of a second flame) is within 10 seconds.2. The total of the total flaming combustion times of the five testpieces is within 50 seconds.3. The flaming combustion time and glowing combustion time of each ofthe test pieces after application of the second flame is within 30seconds.4. No cotton disposed under the test piece is ignited by flaming dripsdropped from one of the test pieces.5. No flaming reaches the gauge length marked 125 mm from the lower endof the test piece.

The results of evaluation of long-term heat resistance (strengthretention) and releasing properties in Examples and Comparative Examplesare shown in Table 3 and Table 4.

TABLE 3 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11Example 12 Example 13 Example 14 Blended PES/PA resins PES/PA 95/5 90/1080/20 70/30 60/40 80/20 Sheet Wholly aromatic polyamide paper materialCorona No Yes No No Yes No No Yes Yes treatment Pressure- No No No No NoNo No Yes (A) Yes (B) sensitive adhesive layer Strength 75 73 68 62 6055 50 60 60 retention (%) Releasing Δ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ properties (beforeimmersed in water) Releasing Δ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ properties (afterimmersed in water at 23° C.) Flame ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ x retardancy

TABLE 4 Comparative Comparative Comparative Comparative ComparativeComparative Comparative example 6 example 7 example 8 example 9 example10 example 11 example 12 Blended PES PES/PA PEN PPS PEN resins PES/PA —— 50/50 30/70 — — — Sheet Wholly aromatic polyamide paper materialCorona No Yes No No Yes Yes Yes treatment Pressure- No No No No No NoYes (A) sensitive adhesive layer Strength 80 78 21 9 35 46 35 retention(%) Releasing x Δ ∘ ∘ Δ x Δ properties (before immersed in water)Releasing x x ∘ ∘ x x x properties (after immersed in water at 23° C.)Flame ∘ ∘ x x x ∘ x retardancy

INDUSTRIAL APPLICABILITY

The electrically insulating resin composition according to the presentinvention can be suitably used as a raw material for the sheet materialfor electrical insulation that needs heat resistance and electricalinsulation properties. Specifically, the electrically insulating resincomposition according to the present invention is suitable forapplications of sheet materials for electrical insulation arrangedaround the coil wire in the motor, and sheets material for electricalinsulation for transformers, bus bars, capacitors, cables, or insulatingfilms for electric circuit boards, for example.

The laminate sheet according to the present invention can be suitablyused as the sheet material for electrical insulation that needs heatresistance and electrical insulation properties. Specifically, thelaminate sheet according to the present invention is suitable forapplications of sheet materials for electrical insulation arrangedaround the coil wire in the motor, and sheets material for electricalinsulation for transformers, bus bars, capacitors, cables, or insulatingfilms for electric circuit boards, for example.

REFERENCE SIGNS LIST

-   1: laminate sheet, 2: resin composition layer, 3: sheet material, 4:    pressure-sensitive adhesive layer

1. An electrically insulating resin composition, comprising apolysulfone resin including a plurality of sulfonyl groups in a moleculeand a polyamide resin, wherein a proportion of the polyamide resin is 1to 45% by mass.
 2. The electrically insulating resin compositionaccording to claim 1, wherein the polysulfone resin is a polyethersulfone resin further including a plurality of ether bonds in amolecule, or a polyphenylsulfone resin further including a plurality ofaromatic hydrocarbons in the molecule.
 3. The electrically insulatingresin composition according to claim 1, wherein the polyamide resincontains an aromatic hydrocarbon.
 4. The electrically insulating resincomposition according to claim 1, wherein the electrically insulatingresin composition has a CTI value of not less than 130 V in a trackingresistance test.
 5. The electrically insulating resin compositionaccording to claim 1, wherein a tear resistance value is not less than20 MPa.
 6. The electrically insulating resin composition according toclaim 1, wherein a strength retention of tensile strength after 250hours have passed at 240° C. is not less than 55%.
 7. The electricallyinsulating resin composition according to claim 1, wherein theelectrically insulating resin composition is formed into a sheet-likeshape.
 8. The electrically insulating resin composition according toclaim 1, wherein the electrically insulating resin composition is usedin application of electrical insulation.
 9. A laminate sheet obtained bybonding a plurality of sheet materials with a resin composition layerinterposed between the sheet materials, wherein the resin compositionlayer comprises a polysulfone resin including a plurality of sulfonylgroups in a molecule and a polyamide resin, and the proportion of thepolyamide resin is 1 to 45% by mass.
 10. The laminate sheet according toclaim 9, wherein the sheet material contains a wholly aromaticpolyamide.
 11. The laminate sheet according to claim 9, wherein thesheet material is paper produced by a wet papermaking method.
 12. Thelaminate sheet according to claim 9, wherein the sheet material is awholly aromatic polyamide paper comprising a wholly aromatic polyamidefiber.
 13. The laminate sheet according to claim 9, wherein the sheetmaterial is a non-woven fabric.
 14. The laminate sheet according toclaim 9, wherein at least a surface of the sheet material on a side ofthe resin composition layer is subjected to a corona treatment.
 15. Thelaminate sheet according to claim 9, wherein the polysulfone resin is apolyether sulfone resin further including a plurality of ether bonds inthe molecule.
 16. (canceled)
 17. The laminate sheet according to claim9, wherein the polyamide resin is a polyamide resin having an aromatichydrocarbon in the molecule.
 18. The laminate sheet according to claim9, further comprising a sheet-like pressure-sensitive adhesive layerhaving pressure-sensitive adhesiveness, wherein the pressure-sensitiveadhesive layer is disposed on at least one of topmost surfaces of thelaminate sheet.
 19. The laminate sheet according to claim 18, whereinthe pressure-sensitive adhesive layer has flame retardancy that meets aUL94 VTM-0 standard.
 20. The laminate sheet according to claim 9,wherein the laminate sheet is configured such that the sheet material isdisposed contacting both surfaces of the resin composition layer, and aninterlayer adhesive force between the resin composition layer and thesheet material is larger than a cohesive failure force of the resincomposition layer and that of the sheet material.
 21. The laminate sheetaccording to claim 9, wherein a strength retention of tensile strengthafter 250 hours have passed at 240° C. is not less than 50%.
 22. Thelaminate sheet according to claim 9, wherein the sheet laminate is usedin application of electrical insulation.